ABSTRACT
The purpose of this study was to investigate the interaction of habitual exercise and candidate gene polymorphisms related to bone on osteo sono-assessment index (OSI) by quantitative ultrasound (QUS) in middle-aged and elderly Japanese. Participants were classified into exercise group (E; n=172, 62.3 ± 7.7 yr) and sedentary group (S; n=65, 58.6 ± 9.2 yr). The OSI was measured with AOS-100. DNA was extracted from blood, and single nucleotide polymorphism in vitamin D receptor, estrogen receptor α, and transforming growth factor-βI were genotyped by TaqMan assay. Group E had significantly lower body weight and body mass index (BMI) than Group S. In men, although Group E was older than Group S, Group E had significantly higher OSI rather than Group S. There was no significant interaction between habitual exercise and each gene polymorphism on OSI. These results essentially remained unchanged even when analysis of covariance was applied after adjustment for age, body weight, and BMI. These results suggest habitual exercise and genetic factors have no interaction on OSI in middle-aged and elderly Japanese. Further investigations are needed to prove the interaction of other gene polymorphisms and exercise.
ABSTRACT
Skeletal muscle is comprised of multiple fiber types. Slow-twitch oxidative muscle fibers have greater capillary density compared with fast-twitch glycolytic fibers of skeletal muscle. To gain insight into the molecular mechanism underlying the difference of capillary density, we investigated whether the basal gene expression of vascular endothelial growth factor (VEGF), a major angiogenesis-related factor, and its transcriptional factors (hypoxia-inducible factor-1α, transforming growth factor-β1, c-jun, and c-fos) differs between these two fiber types of rat skeletal muscle. The mRNA expression of VEGF and its transcriptional factors was significantly higher in slow type fiber of muscle (soleus muscle) compared with fast type fiber of muscle (plantaris and tibialis anterior muscles). These results suggest that the difference of basal gene expression of VEGF and its transcriptional factors between slow and fast fiber types of skeletal muscle may partly contribute to the difference in capillary density between these two fiber types.
ABSTRACT
Arterial compliance progressively decreases with aging. This aging-induced reduction of arterial compliance causes an increase of systolic blood pressure (SBP), whereas regular exercise increases arterial compliance. We hypothesized that an increase in daily physical activity (DPA) produces a beneficial effect on systemic arterial compliance (SAC ; an index of central arterial compliance) and this phenomenon could decrease SBP in the elderly. We investigated the relationship among DPA, SAC, SBP, diastolic blood pressure (DBP), and some other risk factors for cardiovascular and/or cerebrovascular events (total cholesterol, HDL-cholesterol, and HOMA-R) cross-sectionally in 127 elderly persons (42 male, 85 female : aged 74±4 years) . The DPA was estimated by expended calories using an accelerometer. The SAC was calculated from a finger pulse pressure waveform recorded by using PORTAPRES ; and stroke volume obtained from the same pressure waveform based on the volume-clump method. The analyses demonstrated that SBP was directly and decreasingly affected by SAC, and that DPA had an increasing effect on SAC. Furthermore, SBP was directly and increasingly affected by DBP, and DBP was directly and decreasingly affected by both SAC and DPA. Therefore, it is considered that DPA may have suppressive effects on the rise of SBP through the indirect effects of changing SAC and DBP. These findings suggest that an increase in DPA could improve the age-induced reduction of arterial compliance and rise of SBP in elderly humans.
ABSTRACT
To study the effects of prolonged kendo practice in a hot environment on cardiovascular function, certain hemodynamic parameters were measured in 5 male college kendo fencers before and after 1 hour of kendo practice performed at a dry bulb temperature of 30.4t and wet bulb temperature of 26.2°C After kendo practice, body weight was significantly decreased and both hematocrit and blood viscosity were significantly increased. The left ventricular end-diastolic dimension and the left atrial dimension, measured by echocardiography, were significantly reduced after kendo practice, and stroke volume, ejection fraction, and fractional shortening were also significantly decreased after practice. The same fencers were subjected to lower body negative pressure testing designed to reduce the left ventricular end-diastolic dimension to the same degree as kendo practice, and comparable decreases in stroke volume, ejection fraction, and fractional shortening were observed. The ratio of end-systolic wall stress to end-systolic volume index was significantly increased during both kendo practice and lower body negative pressure testing. We conclude that prolonged kendo practice in a hot environment impairs cardiac pump function by reducing preload in parallel with the decrease in venous return, that myocardial contractility may not deteriorate despite marked hemoconcentration, and that fluid intake during practice may prevent deterioration of cardiovascular function.